Monopole elastomeric resonator

ABSTRACT

A device for radiating elastic pressure pulses into a liquid container which comprises a preferably cylindrically shaped body of elastomeric material. A heavy mass is connected to each end of the cylinder of elastomeric material, each mass being further surrounded with a cylinder such that the mass acts as an isolated piston therein, with one mass being coupled to an orbiting mass oscillator.

limited States Patent [111 3,625,484

[72] Inventor Albert G. Bodine 3,089,582 /1963 Musschoot et a1 74/61 X 7877 Woodley Ave., Van Nuys, Calif. 3,417,630 12/1968 Bruderlein. 74/61 91406 3,446,666 5/1969 Bodine 259/1 X [21] Appl. No. 833,293 3,532,325 /1970 Barnett. Jr 259/1 [22] Filed June 16, 1969 2,552,970 5/1951 Horsley et al... 259/1 Patented Dec. 7,1971 2,864,592 12/1958 Camp 259/1 Continuation-impart of application Ser. No. 2,913,602 1 1/1959 Joy 259/1 X 666,398, Sept. 8, 1967, now Patent No. 2,944,520 7/1960 Swanson 259/1 X 3,544,073. This application June 16, 1969, 3,299,722 1/1967 Bodine, Jr. 259/1 X Ser. No. 833,293 3,410,532 11/1968 Bodine 259/1 X 3,410,765 l1/1968 Bodine 259/1 X 541 MONOPOLE ELASTOMERIC RESONATOR 'f Kee 7 Claims 3 Drawing Figs A!l0rneySok0|sk| & Wohlgemuth [52] U.S.Cl 25 /l,

259/72, 74/61 ABSTRACT: A device for radiating elastic pressure pulses [51] Int. Cl B06b 1/16, into a liquid container which comprises a preferably cylindri- BO6b 1/20 cally shaped body of elastomeric material. A heavy mass is Field of Search 259/1, 72, connected to each end of the cylinder of elastomeric material,

DlG.44; 74/61, 87; 173/49; 175/55; 134/184 each mass being further surrounded with a cylinder such that the mass acts as an isolated piston therein, with one mass 1 Reiel'ences Ciled being coupled to an orbiting mass oscillator.

UNITED STATES PATENTS 2,960,3l4 ll/l960 Bodine,.lr. 259 X MONOPOLE ELASTOMERIC RESONATOR This is a continuation in part of application Ser. No. 666,398, filed Sept. 8, 1967, now US. Pat. No. 3,544,073.

In previously filed U.S. Pat. application Ser. No. 666,398 filed Sept. 8, 1967, by the same inventor, there is disclosed a device which is comprised of an elastomeric resonator coupled to an orbiting mass oscillator. The elastomeric resonator is disclosed as being a cylindrical element having one end connected to the oscillator. The cylindrical elastomeric resonator is disposed within a tank of water or other suitable fluid. Articles to be cleaned or washed are then submerged in the liquid bath, the cleaning action benefiting from the sonic energy generated therein.

It has been subsequently found that elastomeric resonators are inclined to resonate in Pat. application number of complex modes. As a result various 30, 1968 vibrate out of phase in relation to other surfaces. Often, when a major portion of the elastomeric resonator is in contact with liquid, the resonator might choose a mode wherein the out of phase motion of adjacent surfaces will cause a cancelling effect so that pressure impulses are neutralized. It is pointed out that this does not happen in all cases. However, many resonators of the elastomeric type will tend to seek this dipole mode of operation since this results in the least amount of work being delivered to the water. In other words, the end effect is that such a resonator would have a strong tendency to actually seek a mode where it has least coupling to the liquid.

Thus, an object of this invention is to provide a novel elastomeric resonator combination involving maximum coupling of the resonator to the liquid body.

The above and other objects of this invention are accomplished by the herein device comprising a'vessel or tank for containing a liquid medium which could be utilized to cause chemical reactions, treat liquids, clean parts, or the like. An elastomeric resonator of rubber or similar material in the shape of a cylinder is provided within the vessel. In one embodiment, the resonator is a solid cylinder of elastomeric material. Affixed to each end of the resonator is a heavy mass or piston element, also preferably cylindrically shaped. Affixed to one wall of the tank, extending into the tank, is a cylinder which serves to surround one of the pistons affixed to an end of the resonator as well as support the device of the invention within the vessel. Also located in this region of the vessel and extending therethrough and coupled to the associated piston is an orbiting mass oscillator to effect vibration of the resonator element through the piston connected thereto. A like cylinder surrounds the piston connected to the opposite end of the resonator, allowing the piston to slide therein when the resonator is vibrated. Means are mounted between the surfaces of the piston opposite those connected to the resonator and the wall of the associated cylinder to cushion the movement of the pistons within the cylinders. In another embodiment of the invention, the resonator element is in the form of either a hollow cylinder, or has a plurality of apertures therein in which stems or pins from the associated pistons are seated.

It is believed that the invention will be better understood from the following detailed description and drawing in which:

FIG. 1 is a partially sectioned side view of the device of this invention.

FIG. 2 is a section view taken along lines 2-2 of FIG. 1.

FIG. 3 is a sectional view of a second embodiment of a resonator element to be useful in this invention.

It is helpful to the comprehension of this invention to make an analogy between a mechanical resonant circuit and an electrical resonant circuit. This type of analogy is well known to those skilled in the art and is described, for example, in chapter 2 of Sonics" by Hueter and Bolt, published in 1955 John Wiley and Sons. In making such an analogy, force F is equated with electrical voltage E, velocity of vibration u is equated with electrical current i, mechanical compliance C,,, is equated with electrical capacitance C mass M is equated with electrical inductance L, mechanical resistance (friction) R,,, is equated with electrical resistance R, and mechanical impedance Z,,, is equated with electrical impedance Z... Thus, it can be shown that if a member is elastically vibrated by a sinusoidal force, F sinwt, 0) being equal to 211' times the frequency of vibration, that Where wM is equal to l/mC,,,, a resonant condition exists, and the effective mechanical impedance Z,,, is equal to the mechanical resistance R,,,, the reactive impedance components 10M and l/mC cancelling each other out. Under such a resonant condition, velocity of vibration u is at a maximum, effective power factor is unity, and energy is most efficiently delivered to the object being vibrated. It is such a high-efficiency resonant condition in the elastic system being driven that is preferably utilized in the methods and devices of this invention to achieve the desired end results.

It is to be noted by reference to equation l that velocity of vibration u is highest where impedance Z is lowest, and vice versa. Therefore, a high-impedance load will tend to vibrate at relatively low velocity, and vice versa. Thus, at an interface between highand low-impedance elements, a high relative movement results by virtue of such impedance mismatch which, as in the equivalent electrical circuit, results in a high reflected wave. Where a low-impedance load, such as water, is present, the acoustic impedance of the elastomer so closely matches that maximum transfer of the vibratory energy is achieved. The mismatch of impedance arises at the interface of the water and parts submerged therein wherein the desired cleaning can occur.

Just as the sharpness of resonance of an electrical circuit is defined as the 0" thereof, and is indicative of the ratio of energy stored to the energy used in each cycle, so also the 0" of a mechanical resonant circuit has the same significance and is equal to the ratio between 10M and R,,,. Thus, high efficiency and considerable cyclic motion can be achieved by designing the mechanical resonant circuit for high Q.

Of particular significance in the implementation of the methods and devices of this invention is the high acceleration of the components of the elastic resonant system that can be achieved at sonic frequencies. It can be shown that the acceleration of a vibrating mass is a function of the square of the frequency of the drive signal times the amplitude of vibration. Under resonant conditions, the amplitude of vibration is at a maximum and thus even at moderately high sonic frequencies very high accelerations are achieved.

In considering equation l several factors are to be noted. First, this equation represents the total effective resistance, mass and compliance in a vibrating circuit, and these parameters are generally distributed throughout the system rather than being lumped in any one component or portion thereof. Secondly, the vibrating system often includes surrounding components, a container holding the water and the water itself.

It is also to be noted that orbiting mass oscillators are utilized in the devices of the invention that automatically adjust their output frequencies to maintain acceleration of the components of the elastic resonant system that can be achieved at sonic frequencies. It can be shown that the acceleration of a vibrating mass is a function of the square of the frequency of the drive signal times the amplitude of vibration. Under resonant conditions, the amplitude of vibration is at maximum and thus even at moderately high sonic frequencies very high accelerations are achieved.

ln considering equation l several factors are to be noted. First, this equation represents the total effective resistance, mass and compliance in a vibrating circuit, and these parameters are generally distributed throughout the system rather than being lumped in any one component or portion thereof. Secondly, the vibrating system often includes surrounding components, a container holding the water and the water itself.

It is also to be noted that orbiting mass oscillators are utilized in the devices of the invention that automatically adjust their output frequencies to maintain resonance with changes in the characteristics of the load. Thus, in situations where we are dealing with parts which are placed in a bath during the operation of the device which will change that load, the system automatically is maintained in optimum resonant operation by virtue of the lock-in characteristics of applicant's orbiting mass oscillators. The vibrational outputs from such orbiting mass oscillators are generated along a controlled predetermined coherent path to provide maximum output along a desired axis or axes. The orbiting mass oscillator automatically changes not only its frequency but its phase angle and therefore its power factor with changes in the resistive impedance load to assure optimum efficiency of operation at all times. Such orbiting mass oscillators are capable of efficiently generating high-level vibrational outputs.

By utilizing as a resonator element an elastomeric material such as rubber, a much greater feedback to the oscillator is accomplished than when the resonator is of a high-impedance material such as, for example, a steel column. This feedback results, since the elastomer, because of its inherently low impedance, provides a greater cyclic stroke for a given frequency at the point where the oscillator is connected. Previously, other low-impedance resonator elements such as air springs have been affixed to an oscillator. However, these elements have lumped constant impedance characteristics. On the other hand, the elastomeric material is a distributed constant system. A distributed constant system has the advantage of being able to accomplish an acoustic level effect where, for example, a high velocity or amplitude vibration at the interface of the oscillator can be converted to a low velocity with a high force at the end of the resonator exposed to the load element.

Further, as indicated, one of the advantages of an orbiting mass oscillator is its lock-in characteristics with the automatic adjustment of operating frequencies to accommodate for sudden changes in environmental reactive impedance. This feedback is best accomplished by a low-impedance resonator, such as the elastomeric element disclosed which gas a large-amplitude vibration to better accomplish the feedback. Additionally, in this same vein, the automatic accommodation for changes in environmental resistive impedance caused by a work load is better fed back to the oscillator through a low-impedance resonator since there is greater activity where the resonator is coupled.

Turning now to FIGS. 1 and 2, there is seen a tank or vessel 11 of cylindrical configuration, which can contain a liquid for cleaning parts and the like. The tank may be provided with an inlet 13 through which the liquid as well as parts to be cleaned can be admitted. Though the embodiment shows the tank disposed in a horizontal position, it should and will be apparent that a vertical disposed tank is also within the scope of the invention and equivalent to that shown. Disposed within the vessel 11 is a solid elastomeric resonator element 15 in the form of a cylinder. Elastomeric resonator 15 is disposed between two movable masses or pistons 17 and 19 respectively. The pistons can be glued or vulcanized or attached by other suitable means to the end of the resonator elements. These pistons will vibrate 180 out of the phase, providing two inductive reactances, with the elastomeric material 15 functioning primarily as a capacitance member.

Disposed through an opening 21 at one end of the vessel 11, and affixed thereto by bolts 23, is a first cylinder element 25 which extends within the vessel and surrounds a portion of the piston 19. Passing through the center of the cylinder member 25 is stem 27 which serves to connect an orbiting mass oscillator 29 to piston 19. The orbiting mass oscillator 29 may be of the inductive type such as seen in US. Pat. No. 3,402,612. ring seals 31 may be provided in the wall of the cylinder member 25 surrounding the axle 27 to prevent leakage of fluid therebetween from the vessel.

A plurality of strut members 32 extend from first cylinder member 25 around the elastomeric resonator element to support a second cylinder member 33 disposed around piston member 17. The strut member 32, four shown by way of example, are particularly seen in FIG. 2. Thus it can be seen that separate cylinder members 25 and 33 respectively surround each piston 19 and 17 respectively. The function of these cylinders will be later explained in the operation of the device. Each cylinder has a shunt compliance disposed therein between it and the associated piston. The compliance can take the form of a rubber tube 35 which can be filled with air, or other suitable gas. This provides a very low impedance to the confined liquid so that piston masses can more freely in their vibratory strokes.

The main acoustic radiating surface of the elastomeric resonator 15 are the sidewalls 37. The motion of the sidewalls 37, as shown by the arrows, is out of phase with the no tion of the piston elements 17 and 19. Because of this, the cylinder elements 25 and 33 are particularly required in this device. Without the cylinder elements the outside ends 39 and 41 of piston elements 17 and 19 respectively would present a dipole effect which would largely neutralize the radiating effect of elastomeric body 15.

In the operation of the device it can be seen that the strut members 32 allow free communication between elastomeric resonator body 15 and the surrounding liquid disposed in vessel 11. Thus the resonator structure will operate as a simple monopole and can be inserted, as shown, into either end ofa suitable tank or vessel.

The orbiting mass oscillator 29 has the particular advantage of having a lock-in" effect whereby it will maintain operation on a stable side ofa resonant curve. The oscillator will adjust its frequency for changes in reactive impedance as well as adjusting its phase angle for changes in resistive impedance. Thus, the oscillator together with the arrangement shown provides a stable and practical system which will stay in resonance even though the material in vessel or tank 11 might be changed by virtue of new material, by chemical reaction or even the release ofgas and the like. The elastomeric resonator of this invention thus provides a substantial area in its sidewalls 37 for acoustic coupling to liquid and material in the tank to be treated.

FIG. 3 discloses a variation of the resonator element 15 shown in the embodiment of FIGS. 1 and 2. The resonator element 41 in this embodiment is provided with a central bore 43. Piston elements 45 and 47 are provided with one or more pin-shaped members 49 and 51 respectively. The function of these pin-shaped members is to provide a spine so as to prevent the elastomeric resonator from going into bending modes. ln other words, the stiff metallic spines force the elastomeric resonator to stay substantially in a longitudinal compression mode. This is particularly desirable since a lateral bending mode would greatly lower the frequency of the system and at the same time present a dipole effect. This would be brought about when the upper side 53 of the resonator 41 would be moving upward generating a positive pressure while at the same instant the opposed side 55 would also be moving upward but generating a negative pressure pulse adjacent the above-mentioned positive pulse, to result in a substantial and undesirable neutralization of energy. Though the center aperture 43 is shown as disposed throughout the resonator 41 in this embodiment, it is obvious that the same effect can be achieved by a plurality of spines or pins in each piston disposed in adjacent openings or apertures in the associated resonator element without necessarily providing through-holes.

lclaim:

1. ln combination:

an elastomeric resonator body having two oppositely disposed end portions,

a piston element affixed to each end portion,

a cylinder surrounding and enclosing each ofsaid piston elements,

and an orbiting mass oscillator coupled to one of said piston elements.

2. The combination of claim 1 further comprising:

sociated piston element.

6. The combination of claim 5 further comprising:

means within each of said cylinders between said piston element and the cylinder to cushion movement of the piston element within the cylinder.

7. The combination of claim 1 wherein:

The elastomeric body is cylindrically shaped having openings therein extending inwardly from each end,

and said piston elements are provided with corresponding spines fitted within said openings. 

1. In combination: an elastomeric resonator body having two oppositely disposed end portions, a piston element affixed to each end portion, a cylinder surrounding and enclosing each of said piston elements, and an orbiting mass oscillator coupled to one of said piston elements.
 2. The combination of claim 1 further comprising: structural means connecting one cylinder to the other.
 3. The combination of claim 2 further comprising: a tank for containing a liquid enclosing said elastomeric body, piston elements and cylinders.
 4. The combination of claim 3 wherein: one of said cylinders is affixed to a wall portion of said tank.
 5. The combination of claim 4 wherein: said oscillator is disposed outside of said tank and further comprising: an elastic coupling member extending from said oscillator through said cylinder in said wall connecting the associated piston element.
 6. The combination of claim 5 further comprising: means within each of said cylinders between said piston element and the cylinder to cushion movement of the piston element within the cylinder.
 7. The combination of claim 1 wherein: The elastomeric body is cylindrically shaped having openings therein extending inwardly from each end, and said piston elements are provided with corresponding spines fitted within said openings. 